I used a mixture of organic potting soil with sand and perlite in it and some gravel. The branches are from my trees out back and I just wash them with some soap and water. Live branches rarely have internal parasites like dead wood. Dead wood is either washed in a hot bleach solution or is washed and then baked to kill any insects living in it. I've used them for almost 7 years without issue.
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2.2~Cornsnakes
3.6~Green tree python
4.3~ATB
1.1~Sibon Nebulatus
1.0~Eyelash viper
1.1~False Water Cobras
Dogs, cats, horses....
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